1. Technical Field
Aspects of the present invention relate to a projector.
2. Related Art
Various types of projectors have been proposed so far, such as a projecting device disclosed in Japanese Patent Provisional Publication No. 2003-280091. The projecting device is designed to be set on a table which is used for a meeting, etc. and to project video images onto the table.
As another example of a projector of this type, there has been proposed a projector device in Japanese Patent Provisional Publication No. 2002-268142. The projector device is configured to project images by use of light emitted from a light source installed in the projector device.
In the projector device, when a tilt sensor detects the tilt of the projector device and generates an output signal representing the detected tilt, a judgment is made to determine as to whether change in the output signal has continuously exceeded a predetermined output level for a predetermined time period or longer.
When the change in the output signal does not continuously exceed the predetermined output level for the predetermined time period, the projector device judges that the device is in a stable tilt state and the light source keeps on emitting the light. On the other hand, when the change in the output signal continuously exceeds the predetermined output level for the predetermined time period or longer, the projector device judges that the device is in an unstable tilt state and stops the light emission from the light source.
In the projecting device disclosed in the former publication, contents of the projected image are constant and do not depend on a horizontal position (e.g. on a table) and a vertical position of the screen on which the projector device (e.g. on a wall of a room) is placed.
Therefore, even when a menu image (an image indicating one of various kinds of menus such as an operation menu) is projected by the projecting device as an auxiliary image other than principal (main) video images inputted from an external device, the same menu image is projected irrespective of whether the screen is placed in the horizontal position or in the vertical position.
In such a configuration, the menu image can include an unnecessary menu item, depending on the position of the screen. Therefore, the use of the projector may not necessarily be easy for the user to use when the menu image is in uniform as above with no regard to the screen position.
Further, if the projecting device disclosed in the former publication is used as a wall-mounted projector, the projected image can be upside down or rotated at 90 degrees depending on the position of installation of the projector with respect to the projection surface. Thus, the projected image may not be properly oriented depending on the installation position of the projector.
Meanwhile, the projector device disclosed in the latter publication continues emitting the light from the light source irrespective of the tilt angle of the device, unless the change in the output signal of the tilt sensor continuously exceeds the predetermined output level for the predetermined time period.
In such a state, if the projector device is moved for changing its projecting position, attitude, or orientation, the light from the light source can accidentally enter eyes of people around the projector device and may harm eyes of those people.